Shell fabric with motion followability

ABSTRACT

A stretch fabric has excellent snap back performance. The stretch fabric is a warp knitted fabric formed from hard yams and elastic yams, wherein the included angle (α) between a sinker loop (2) of the elastic yam and the knitting direction of a needle loop is 0-10°, and the included angle (β) between a sinker loop (4) of the hard yam and the knitting direction of a loop is 5-85°. Particularly under high-speed stretching and recovery motion conditions, a wearing pressure increase caused by an elongation stress and a wearing pressure decrease caused by a delayed recovery can be effectively inhibited. Moreover, the wearing comfort can be maintained and muscle vibration can be prevented.

TECHNICAL FIELD

This disclosure relates to a stretch fabric with high speed snap backperformance and, in particular, to a warp knitted fabric formed fromhard yarns and elastic yarns.

BACKGROUND

An elastic stretch fabric formed by polyurethane fibers has relativelygood snap back performance under low speed and constant speedconditions, but it will not recover in time after stretching under highspeed and abrupt-acceleration conditions. Moreover, different knittingstitches generate different binding forces on the stretch fabric, andthe binding force will also affect the expansion and contractionperformance of the stretch fabric, thereby affecting the snap backperformance.

At present, most of the warp knitted stretch fabrics on the market areoften only suitable for sports under low speed and constant speedconditions. For example, Chinese Patent Publication No. CN202323318Udiscloses a stretch warp knitted fabric knitted by three guide bars, thesurface guide bar knits with 20D polyamide yarn, and then the two guidebars respectively knit with 40D, 70D spandex weft laid-in stitches, andthe obtained stretch fabric has superior elasticity and softness and iscomfortable to wear.

As another example, Chinese Patent Publication No. CN205077227Udiscloses a novel warp knitted body shaping stretch fabric knitted bythree guide bars, specifically, the front guide bar is made of syntheticfiber filaments and knitted by tricot stitches; the middle guide baralternately knits by using spandex via tricot stitches and two needlestitches; and the back guide bar knits by using spandex via reservetricot stitches, and the obtained stretch fabric has different bodyshaping effects on different portions of the body.

As yet another example, Chinese Patent Publication No. CN102648313Adiscloses an elastic warp knitted fabric, wherein elastic yarns areknitted with knit stitches such as full tricot stitches, two needlestitches or warp sateen stitches, hard yarns are knitted with warp pilestitches or 5-needle warp sateen stitches, the tilt angle of the mesh is20 to 70 degrees, the obtained stretch fabric has excellent elongationbalance and elongation recovery in the warp and weft directions, iswell-fitting and unlikely to generate pattern deformation during wear,and has excellent snap back performance, thereby being able to improveits sports functions.

It is well known that top-level athletes experience high-speed andabruptly-variable-speed motion states during exercise. However, none ofthe above publications provide relevant solutions for the snap backperformance of the stretch fabric under high-speed andabrupt-acceleration conditions.

It could therefore be helpful to provide a stretch fabric havingexcellent snap back performance, which is particularly suitable formotion under high speed and abrupt-acceleration states.

SUMMARY

We therefore provide:

-   -   A stretch fabric with snap back performance is a warp knitted        fabric formed by hard yarns and elastic yarns, wherein the        included angle between a sinker loop of the elastic yarn and the        knitting direction of a loop is 0-10°, and the included angle        between the sinker loop of the hard yarn and the knitting        direction of the loop is 5-85°.    -   The stretch fabric with snap back performance can effectively        prevent a wearing pressure increase caused by an elongation        stress and a wearing pressure decrease caused by a delayed        recovery, particularly under high-speed and abrupt-acceleration        conditions so that wearing comfort can be maintained, and muscle        vibration can be prevented. In addition, the stretch fabric is        less prone to problems such as breaking and tearing even when        being used for a long period of time, and has a long-lasting        elastic effect. The stretch fabric can be used to make garments        suitable for athletes and the like, and is particularly suitable        to make tight-fitting athletic wear for top athletes to wear        under high speed and abrupt-acceleration conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a fabric structure of elastic yarns ina stretch fabric, wherein 1 represents a needle loop of the elasticyarn, 2 represents an sinker loop of the elastic yarn, and α representsthe included angle between the sinker loop of the elastic yarn and theknitting direction.

FIG. 2 is a schematic diagram of a fabric structure of sinker loop in astretch fabric, wherein 3 represents the needle loop of the hard yarn, 4represents the sinker loop of the hard yarn, and β represents theincluded angle between the sinker loop of the hard yarn and the knittingdirection.

FIG. 3 is a structural schematic diagram of a flex testing instrument,wherein 5 represents a flex testing fabric specimen, 6 represents anannular inner frame, 7 represents an annular outer frame, and 8represents a fixing screw.

FIG. 4 is a structural schematic diagram of the flex testing instrumentin a test process, wherein 9 represents a sagging area of the flextesting fabric specimen.

DETAILED DESCRIPTION

The stretch fabric with excellent snap back performance is a warpknitted fabric formed by hard yarns and elastic yarns, wherein theincluded angle between a sinker loop of the elastic yarn and theknitting direction is 0-10°, and the included angle between the sinkerloop of the hard yarn and the knitting direction is 5-85°.

We believe that the specific structural characteristics of the elasticyarns and the hard yarns in the stretch fabric are key factorsdetermining the snap back performance of the stretch fabric. For thespecific structural features described above, it is characterized by theincluded angle formed between the sinker loop and the knittingdirection. The specific angle size is observed by an SEM electronmicroscopy or a digital microscope.

The structure of the elastic yarn in the stretch fabric is mainlycomposed of two portions, namely a needle loop and a sinker loop,wherein the needle loop is sequentially connected along the knittingdirection and the stretchability can be maximized in the knittingdirection. To control the stretchability of the sinker loop portion, itis required that the stretchability of the sinker loop portion should becontributed as much as possible in the knitting direction of the loop,that is, the greater projection amount of the sinker loop of the elasticyarn in the knitting direction of the loop is better, that is, thesmaller included angle between the sinker loop and the knittingdirection of the loop is better. When the included angle is minimum andtends to 0°, stretchability of the sinker loop is almost entirelycontributed to the knitting direction of the loop. When the includedangle is greater than 10°, orthogonal decomposition is performed on thesinker loop of the elastic yarn, an obvious component is generatedduring projection in the horizontal direction, that is to say,stretchability of the extension line is not concentrated to the knittingdirection, which is disadvantageous in improving the snap backperformance. Thus, to maximize the snap back performance effect, it isrequired that the included angle between the sinker loop of the elasticyarn and the knitting direction should be 0° to 10°, and preferably 2°to 9°.

The structure of the hard yarn in the stretch fabric is also composed ofa needle loop and a sinker loop. The needle loop of the hard yarn isalso distributed in the knitting direction, that is, the telescopicmotion direction, and the needle loop of the inelastic yarn isoverlapped with the needle loop of the elastic yarn. On one hand, thehard yarn itself has almost no stretchability so it can only provide atelescopic space for the elastic yarn via deformation of the loopstructure; and, on the other hand, as the strength of the hard yarn ishigher than that of the elastic yarn, the hard yarn loop plays a certain“reinforcing” effect on the elastic yarn loop that can improve thestrength of the stretch fabric.

The extension line of the hard yarn can not only ensure the connectionbetween the loops to smoothly form the fabric, but also can restrict thestretchability of the stretch yarn to some extent, that is, affect thesnap back performance of the stretch fabric. For the entirety of thestretch fabric, the snap back performance, the strength and otherproperties must be evenly distributed, which requires that thestructures of the sinker loop of the hard yarn in the stretch fabricmust be consistent, that is, the angles between the sinker loop of allhard yarns and the knitting direction of the needle loops should beconsistent. When the included angle between the extension line of thehard yarn and the knitting direction of the needle loop is less than 5°,the distribution of the sinker loop is biased toward the knittingdirection of the loops, and links between the transverse loops arerelatively small, and it is difficult to ensure the smooth knitting offabric; when the included angle between the sinker loop of the hard yarnand the knitting direction of the needle loop is 86° to 90°, the sinkerloop of the hard yarn is substantially perpendicular to the knittingdirection of the needle loop. For the elastic yarn parallel to thetelescopic motion direction, application of the performance is greatlyrestricted, which is not conducive to implementation of the snap backperformance. Therefore, to maximize snap back performance, the includedangle between the sinker loop of the hard yarn and the knittingdirection should be 5° to 85°, and is preferably 7° to 65°.

The elastic yarn is not particularly limited, and may be a polyurethanefiber (also called spandex, referred to as PU), or a single-componentpolyester fiber or a two-component side-by-side polyester fiber, or ahigh-shrinking false twisted yarn. In view of the original intention ofthe design of the stretch fabric with the snap back performance, it isdesirable that the wearing pressure increase caused by the elongationstress during elongation can be reduced, and the wearing pressuredecrease caused by the delayed recovery of the stretch fabric can alsobe reduced due to the use of the elastic yarn. The stretch fabric isrequired to have small corresponding tensile stress when a largeelongation amount is obtained. It is required that the stretch fabricshould have good instantaneous recovery and a higher recovery forceretention rate. In addition, from the perspective of durability, it isrequired that the stretch fabric should maintain its original size andelasticity after repeated reciprocating expansion and contraction.Therefore, the elastic fiber is preferably the polyurethane fiber havinglow stress and high elongation property, can recover after stretching,and has a high recovery strength maintaining rate and good durability,and more preferably soft elastic spandex. The soft elastic spandexrefers to a polyurethane fiber obtained after reaction of polyether diolhaving a side chain and a diisocyanate compound with two or more diaminecompounds, wherein the molar ratio of ethylenediamine contained in thediamine compound to a branched aliphatic diamine compound having 3 to 5carbon atoms is 98:2 to 82:18. There are many types of spandex availableon the market such as LYCRA® FUSION™ spandex produced by the INVISTA,Creora® PowerFit spandex by the Hyosung, and Qianxi spandex produced byHuafon Spandex Co., Ltd. Compared to the spandex described above, thesoft elastic spandex herein has superior softness and elasticity, andits soft elastic index is 0.75-1. The soft elastic index refers to aratio of the elongation stress at 100% elongation to the recovery stressof 100% recovery after elongation to 300%. The soft elastic indexindicates that the soft elastic spandex has a high recovery forceretention rate, which is advantageous in improving the elastic recoveryof the stretch fabric and reducing the incidence of delayed recovery,thereby improving the motion followability of the stretch fabric.

The higher the content of the elastic yarn is, the more sufficient andsignificant the effect of the elastic yarn is played, and the better thesnap back performance of the stretch fabric is. Theoretically, thestretch fabric composed of 100% elastic yarns has the best snap backperformance, but such a stretch fabric may have problems such asbreaking and tearing due to insufficient strength. To ensure that thestrength performance of breaking tearing and the like of the stretchfabric can reach the standard, the hard yarns, that is, “hard yarns” areused for reinforcement, the higher the content of the hard yarns is, thehigher the strength performance indexes such as breaking and tearing is,but relatively speaking, the lower the content of the elastic yarns is,the more easily the hard yarns exert the inhibition on the performanceof the elastic yarns, and it may not get a good snap back performanceeffect. Therefore, it is necessary to find a balance point between thesnap back performance and the strength performance, and to maximize thesnap back performance under the premise of ensuring the strength.Therefore, the content of the elastic yarns is preferably 50 to 90% byweight.

Considering that if the distribution density of the elastic yarns in thestretch fabric is too small, the elastic stress of the stretch fabric istoo small, and the work done to overcome the elastic stress during thestretching process is relatively small. Although it becomes easy tostretch, there is also a problem of insufficient wearing pressure and atendency of worse muscle vibration prevention effect, and the recoverystress becomes small, and the timely recovery performance at high speedand abrupt acceleration also tends to deteriorate. On the other hand, ifthe distribution density of the elastic yarns is too large, the elasticstress and the recovery stress of the stretch fabric are too large.Although the timely recovery performance at high speed and abruptacceleration is remarkably improved, work done to overcome the elasticstress during the stretching process becomes relatively large so that itmay be unlikely to stretch and, correspondingly, if the wearing pressureis too large, the oppressing sensation on the human body will be toostrong, and the wearing comfort will be worse. Therefore, thedistribution density of the elastic yarns is preferably 30 to 200w/inch.

The hard yarn preferably has an elongation of 5 to 50%. Since the yarnneeds a certain amount of stretching for bending and circling, in aknitting process, if the elongation is less than 5%, the yarn is liableto break, and the knitting requirement may not be satisfied. When theelongation is greater than 50%, the yarn is likely to be over-drafted inthe knitting process so that the yarn feeding may not be smooth, andpassability may be poor. The fiber raw material of the hard yarnsatisfying the above elongation range can be a natural fiber such ascotton or wool, or can be an artificial fiber such as viscose or modal,or a synthetic fiber such as nylon or polyester. From the viewpoints ofhigh efficiency and cost of knitting, chemical fiber filaments such asnylon and polyester are preferred. The nylon herein includes ordinarynylon and modified nylon (e.g., having hygroscopic groups or the like),and the polyester includes ordinary polyester and modified polyester(e.g., having cationic dyeable groups or the like).

In addition to the influence on the contents of the hard yarns and theelastic yarns, the thickness of the yarn also affects the gram weight ofthe stretch fabric. If the gram weight is too large, the stretch fabricis too thick, the wearing pressure on the human body is relativelylarge, and the friction force with the skin surface is relatively large,which is not conducive to obtaining a good sport following effect, andalso affects knitting comfort. If the gram weight of the stretch fabricis too small, the stretch fabric is too light and thin such that theanti-transparent performance and the like are not ideal enough to meetgeneral cloth requirements. Therefore, it is necessary to make areasonable choice on the fineness of the yarn used. The hard yarnpreferably has a fineness of 10 to 100 deniers (abbreviated as D), andmore preferably 10 to 50 D; and the elastic yarn has a fineness ofpreferably 30 to 300 D, and more preferably 70 to 140 D. In terms of thegram weight of the shell fabric and the like, the hard yarn is selectedas a relatively fine yarn as much as possible, and the elastic yarn isselected as a relatively coarse yarn as much as possible. Therefore, itis preferred that the fineness of the elastic yarn is 1 to 10 times,more preferably 1 to 5 times, as large as the fineness of the inelasticyarn.

We adopt a warp knitted stitch for knitting, and the number of guidebars is preferably 2 or 3. When the number of guide bars is too large,and the shell fabric is too thick, acquisition of the snap backperformance may be effected. The stretch fabric knitted by two guidebars is used as an example, the stretch fabric is divided into fourhierarchical structures from the front face of the process to thereverse side of the process, which are respectively a loop surface of afront guide bar the loop surface of a back guide bar, an extension linesurface of the back guide bar and the extension line surface of thefront guide bar and the structure formed by the four layers that aresleeved and connected to each other has better structural compactnessand stability than the single-side weft-knitted fabric or a knittedfabric, and can ensure the stable performance of the snap backperformance. During knitting, it is preferred that the elastic yarn islocated in the back guide bar so that both the loop surface and theextension line surface are located in the inner layer to prevent thesame from being worn and to improve the durability. The stretch fabricknitted by three guide bars is used as an example, the stretch fabric isdivided into six hierarchical structures from the front face of theprocess to the reverse side of the process, which are respectively theloop surface of the front guide bar, the loop surface of a middle guidebar, the loop surface of the back guide bar the extension line surfaceof the back guide bar, the extension line surface of the middle guidebar and the extension line surface of the front guide bar. With respectto the stretch fabric formed by the three guide bars, it is preferredthat the front guide bar and the middle guide bar adopt a threading modeof threading one and leaving one and reversely laying the yarns, in thisway, the stretch fabric can be prevented from being too thick on onehand, and the stretch fabric structure can be more stable on the otherhand.

The stretch fabric is produced by conventional refining and dyeing andsorting of a knitted fabric obtained by knitting, and the specificprocessing conditions are not particularly limited. In the finishingprocess, water-absorbing soft resin can be adopted to further endow asoft and comfortable hand feeling and good water absorption property tothe stretch fabric. The water-absorbing soft resin herein refers to aresin finishing agent having a hydrophilic group and having alubricating effect, and a commercially available product can be directlyused as the water-absorbing soft resin, or can be synthesized accordingto a known technique, and the dosage thereof is adjusted according tothe fiber components of the stretch fabric, is preferably 5 to 30 g/Land is more preferably 10 to 20 g/L.

In view of the fact that during the actual wearing, the stretch fabricwill generate the delayed recovery phenomenon in a reciprocating motionprocess, to recover the phenomenon, the stretch fabric is made into acylinder having a diameter of 10 cm and a height of 5 cm, thereciprocating motion is simulated under the condition of 50% elongationand 3 times/second speed expansion and contraction, and it is found thatthe cylindrical stretch fabric depresses inward in the motion processdue to the delayed recovery, the cylindrical edge of the deformedstretch fabric forms a sealed area with the vertical portion, that is, adeformation area generated for the delayed recovery. To obtain asuperior snap back performance effect, the sagging area formed bydepression of the contour portion of the stretch fabric is preferablynot greater than 2 cm², and is further preferably not greater than 1.5cm².

Preferably, when wearing the clothes made of the stretch fabric, theclothes pressure at the middle of the thigh in a static state ismeasured as 1.5-2.0 kPa, and the recovery stress of the stretch fabricat the corresponding portion is 1.5-3.0 N. Within the above range, thewearing comfort can be guaranteed, and the vibration of thigh musclescan be effectively prevented.

Preferably, the tear strength of the stretch fabric is measured as 9.8 Nor more under the test conditions of JIS L 1096:2010 D method; and underthe test conditions of the JIS L 1096:2010 A method, the burst strengthof the stretch fabric is measured as greater than 290 kPa. Within theabove range, it can be ensured that the clothes made of the stretchfabric are not easily torn during the multiple times of wearing, takingoff and use, and are not easily broken.

Our fabrics and methods will now be described in more detail by way ofexamples and comparative examples. The performance indexes involved inthe examples are measured by the following methods.

(1) The Included Angle Between the Sinker Loop and the KnittingDirection of the Loop

Step 1, cutting a 150 mm×150 mm sample and observing the sample at amagnification of 20 times by using an SEM electron microscope or adigital microscope;

Step 2, selecting two loops (of the elastic yarn or the hard yarn) onany knitting direction, wherein the two are preferably separated by 25to 50 loops in the knitting direction; respectively using the highestpoints of the needle loop of the two selected loops as marking points,connecting the two marking points to obtain a sinker loop to serve as areference line in the knitting direction of the loop, and using thesinker loop as the datum line to measure the angle of the extension lineof the loop;

Step 3, randomly selecting 12 loops at the top, bottom, left and rightpositions of the sample, wherein 3 loops are located at each position,measuring the included angles between the sinker loop of the loops (theelastic yarns or the hard yarns) at different positions and the datumline (or a parallel line of the datum line) by using a protractor, andusing the average value as the included angle between the extension line(of the elastic yarn or the hard yarn) and the knitting direction of theloop.

(2) Sagging Area

Meaning: the size of the area of the deformed portion due to the delayduring the reciprocating telescopic motion of the stretch fabric underspecific speed and elongation conditions. The smaller the value is, thebetter the motion followability of the stretch fabric is. The specificmethod is as follows:

Test equipment: De Mattia repeated fatigue testing machine DC-210 type(made by the Daiei Scientific Precision Manufacturing Co., Ltd.)

Step 1, sampling: on any portion of the stretch fabric, horizontallymeasuring a length of 350 mm to serve as a marking line, longitudinallymeasuring a length of 120 mm to serve as a marking line, cutting alongthe marking line to obtain a rectangular sheet sample with length 350mm×width 120 mm, and sampling 5 pieces by using the same method;

step 2, pre-treatment of the sample fabric: clamping the upper and loweredges of the sample fabric on upper and lower jaws of the repeatedfatigue testing machine and fixing the same, then setting thepre-elongation as 80%, and performing reciprocating pre-stretchingtreatment for 10 times so that the bent yarns in the stretch fabric arestraightened;

step 3, cylindrical treatment and installation of the sample fabric:adhering the pretreated sample fabric along the knitting direction bytapes or the like to form a cylindrical shape; preparing a pair ofannular fixing devices respectively formed by the reedination of innerframes and outer frames, sleeving the cylindrical sample fabric on theouter side of the annular inner frame, and then sleeving the annularouter frame on the outer side of the cylindrical sample fabric, andfixing it with screws or the like firmly to obtain a cylindrical testtool having an effective diameter of 10 cm and a height effective sizeof 5 cm; and then mounting the cylindrical test tool on the repeatedfatigue testing machine as a whole, wherein in the whole installationand fixing process, the stretch fabric should be smooth and free fromslack, and there should be no accidental stretching, that is, thestretch fabric should not be tensioned to not affect the later testresults;

step 4, test: setting the maximum elongation of the stretch fabric as50%, wherein the test process is specifically low speed (1 time/second),medium speed (2 times/second), high speed (3 times/second), medium speed(2 times/second) and low speed (1 time/second), and respectively testingfor 1 minute at the stretching speed. The whole test process is recordedby a high-speed camera, and the high-speed camera used here refers to acamera with a frame rate of 100-1000 fps;

step 5, quantification: the relaxation area generated under a high speed(3 times/second) condition is the evaluation index of the snap backperformance. An image taken when the above stretch fabric recovers tothe initial position state after being subjected to the telescopic testfor 1 minute under the high speed (3 times/second) is picked out andprinted. The area (in cm²) of the above-described deformed portion ismeasured on printing paper by using an area meter or other imageprocessing tools. In addition, the sagging areas under the low speed (1time/second) and the medium speed (2 times/second) can also be measuredaccording to the same test method, and the data measured under the speedconditions can be compared and analyzed to evaluate the snap backperformance of the stretch fabric at various speeds. Furthermore, therelationship curve between the sagging area and the correspondingexpansion speed can be made based on these data, and the advantages anddisadvantages of the snap back performance of the stretch fabric can beobserved and judged by observing the change trend of the curve; and

step 6, testing N number and deviation value: the 5 sample fabric areall tested according to the above steps 1 to 5, and the average value istaken as the test result of the sagging area when the data are valid.Whether the data are valid is determined by the change coefficient ofthe data. The change coefficient of a group of data is obtained bydividing a standard deviation value by the average value of the group ofdata, that is, the change coefficient=standard deviation value/averagevalue, if the change coefficient of a group of test data is less than0.1, the group of test data is regarded as valid data, otherwise thetest is performed again.

(3) Clothes Pressure

Meaning: indicating the contact pressure of the clothes on the humanbody. The smaller the value is, the smaller the pressure of the clotheson the human body portion is, and the more unfavorable the prevention ofthe muscle vibration is. The length 500 mm×width 100 mm sample fabric issewed into a cylindrical test sample after reserving 50 mm on the twoends on the length direction by using the Pressure Converter-5S3037-5Sclothes pressure tester manufactured by the Japan AMI Co., Ltd., thecircumference of the sewed cylindrical test sample is 400 mm, and thenthe cylindrical test sample is sleeved flatly at the middle of the thighof a dummy, the circumferential extension reaches 500 mm (thecorresponding elongation of use reaches 25%), and the test is performedfor three times, and the average value is taken.

(4) Recovery Stress

Meaning: indicating the size of stress when the stretch fabric attemptsto return to the original position after being stretched. The larger thevalue is, the better the recovery of the stretch fabric is. The testmethod is as follows:

a. Sample cloth: horizontal 100 mm×wale 150 mm, 6 pieces (3 pieces areused for testing the elongation and 3 pieces are used to test therecovery stress);

b. using an electronic universal tensile testing machine equipped withan automatic recording device (made by the Meitesi Industry System(china) Co., Ltd, model number CMT6103), setting a clamping amplitude of2.54 cm and a clamping distance of 7.6 cm, and applying 29 mN (3 g)initial load;

c. stretching to 10 N at a stretching speed of 10 cm/min, reading thecorresponding elongation at this time, and further obtaining theelongation. The average value measured by the three pieces of samplecloth on the same direction is used as the final elongation;

d. Stretching at a tensile speed of 10 cm/min to 80% of the elongationobtained in the step c, holding for 1 minute, returning to the originalposition at the same speed, and holding for 3 minutes; and

e. After repeating the operation of the step d for 5 times, the dataautomatically recorded by the device is plotted to draw a relationshipcurve corresponding to the elongation stress and the elongation, readingthe recovery stress corresponding to recovery to 25% elongation, testingthe three pieces of sample cloth according to the above method, andtaking the average value as the test result of the recovery stress.

(5) Tear Strength

The test is carried out in accordance with the Japanese IndustrialStandard JIS L 1096:2010 D method. The larger the value is, the higherthe tear strength of the stretch fabric is, and the less likely it is tobe torn.

(6) Burst Strength

The test is carried out in accordance with the Japanese IndustrialStandard JIS L 1096:2010A. The larger the value is, the higher the tearstrength of the stretch fabric is, and the less the cracking possibilityis.

Example 1

On the RSE4 Raschel warp knitting machine (machine number E32, machinewidth 136 inches), 40D-34f-nylon FDY (made by the Toray Synthetic FiberCo., Ltd.) is selected as the yarn of the front guide bar 100D ordinaryspandex bare yarn (made by Huafon) is used as the yarn of the back guidebar a tricot stitch/pillar stitch of crossing two needles by the frontguide bar and crossing one needle by the back guide bar is adopted, thefront guide bar and the back guide bar perform full threading, theknitting is performed to obtain a gray fabric, and then our stretchfabric is made by refining and dyeing and sorting, and reference can bespecifically made to Table 1.

Refining conditions: caustic soda 2 g/L, scouring agent 2 g/L, 95° C.×20min, bath ratio 1:20; dyeing: 95° C.×30 min, and reduction cleaning: 80°C.×20 min.

Example 2

On the HKS4 high-speed tricot machine (machine number E32, machine width136 inches), 20D-12f-cationic dyeable polyester FDY (referred to asCD-PET, made by the Toray Synthetic Fiber Co., Ltd.) is used as the yarnof the front guide bar 140D ordinary spandex bare yarn (made by theHyosung Co., Ltd.) is used as the yarn of the back guide bar amiss-lapping/pillar stitch of crossing 1-2 needles by the front guidebar and crossing one needle by the back guide bar is adopted, the frontguide bar and the back guide bar perform full threading, the knitting isperformed to obtain a gray fabric, and then our stretch fabric is madeby refining and dyeing and sorting, and reference can be specificallymade to Table 1.

Refining conditions: caustic soda 2 g/L, scouring agent 2 g/L, 95° C.×20min, bath ratio 1:20; dyeing: 120° C.×60 min, and reduction cleaning:80° C.×20 min.

Example 3

The 280D soft elastic spandex bare filament (manufactured by the TORAYOPELONTEX Co., Ltd.) is used as the yarn of the back guide bar, a mannerof one threading and one empty is adopted, the rest conditions are thesame as those in Example 2, our stretch fabric is made, and referencecan be specifically made to Table 1.

Example 4

Knitting is performed on the HKS4 high-speed tricot machine (machinenumber E32, machine width 136 inches), the rest conditions are the sameas those in Example 1, our stretch fabric is made, and reference can bespecifically made to Table 1.

Example 5

The 140D soft elastic spandex bare filament (manufactured by the TORAYOPELONTEX Co., Ltd.) is used as the yarn of the back guide bar the restconditions are the same as those in Example 2, our stretch fabric ismade, and reference can be specifically made to Table 1.

Example 6

Knitting is performed on the RSE4 Raschel warp-knitting machine (machinenumber E28, machine width 136 inches), the rest conditions are the sameas those in Example 1, our stretch fabric is made, and reference can bespecifically made to Table 1.

Comparative Example 1

Knitting is performed on the RSE4 Raschel warp knitting machine (machinenumber E32, machine width 136 inches), the rest conditions are the sameas those in Example 5, the stretch fabric is made, and reference can bespecifically made to Table 1.

Comparative Example 2

Knitting is performed on the HKS4 high-speed tricot machine (machinenumber E28, machine width 136 inches), the rest conditions are the sameas those in Example 4, the stretch fabric is made, and reference can bespecifically made to Table 1.

Comparative Example 3

The 40D-34f-nylon FDY (made by the Toray Synthetic Fiber Co., Ltd.) isselected as the yarn of the front guide bar, 100D ordinary spandex bareyarn (made by Huafon) is used as the yarn of the back guide bar thetricot stitch/tricot stitch of crossing two needles by the front guidebar and crossing two needles by the back guide bar is adopted, theknitting is performed to obtain the gray fabric, the rest conditions arethe same as those in Example 1, the stretch fabric is made, andreference can be specifically made to Table 1.

TABLE 1 Comparative Comparative Comparative Item Example 1 Example 2Example 3 Example 4 Example 5 Example 6 Example 1 Example 2 Example 3Raw Front guide bar nylon CD-PET CD-PET nylon CD-PET nylon CD-PET nylonnylon material Back guide bar Ordinary Ordinary Soft Ordinary SoftOrdinary Soft Ordinary Ordinary spandex spandex elastic spandex elasticspandex elastic spandex spandex spandex spandex spandex Stitch TricotMiss- Miss- Tricot Miss- Tricot Miss- Tricot Tricot stitch/ lapping/lapping/ stitch/ lapping/ stitch/ lapping/ stitch/ stitch/ pillar pillarpillar pillar pillar pillar pillar pillar Tricot stitch stitch stitchstitch stitch stitch stitch stitch stitch Runner length (mm/rack)1300/800 1200/800 1200/800 1300/800 1200/800 1300/800 1200/800 1300/8001300/1050 Fineness of the hard yarn (D) 40 20 20 40 20 40 20 40 40Elastic yarn Content (%) 58 81 81 58 81 58 81 58 64 Distribution 39 7428 39 74 39 74 39 39 density (w/inch) Included angle Elastic yarn  9° 5°  5°  2°  5° 2° 11° 2° 12° between the Hard yarn 14° 65° 65° 14° 65°7° 65° 4°  4° sinker loop and the knitting direction Snap backperformance 1.9 1.7 1.5 1.1 0.9 1.6 2.9 2.5 3.3 (sagging area, cm²)Middle portion Clothes 1.6 1.5 1.2 1.8 1.7 2.1 1.4 1.6 2.3 of the thighpressure (Kpa) Recovery 2.1 1.9 1.6 2.5 2.3 2.9 1.7 1.8 3.1 stress (N)Longitudinal tear strength (N) 11.5 12.6 9.9 11.7 13.4 14.5 9.3 10.114.2 bursting strength (Kpa) 354 368 292 363 372 417 284 297 381 Generaleffect Good Good Good Excellent Excellent Good Poor Poor Poor

According to the above table,

(1) It can be seen from Example 1 and Example 4 that, under the sameconditions, the stretch fabric in which the included angle between thesinker loop of the spandex and the knitting direction is 9° is comparedto the stretch fabric in which the included angle between the sinkerloop of the spandex and the knitting direction is 2°, the sagging areaof the latter is small, and the snap back performance is more excellent.(2) It can be seen from Example 2 and Example 5 that, under the sameconditions, the stretch fabric using the ordinary spandex is compared tothe stretch fabric using the soft elastic spandex, the sagging area ofthe latter is small, and the snap back performance is more excellent.(3) It can be seen from Example 3 and Example 5 that, under the sameconditions, the stretch fabric in which the spandex distribution densityis 28 w/inch is compared to the stretch fabric in which the spandexdistribution density is 74 w/inch, the sagging area of the latter issmall, and the snap back performance is more excellent.(4) It can be seen from Example 4 and Example 6 that, under the sameconditions, the stretch fabric in which the included angle between thesinker loop of the hard yarn (nylon) and the knitting direction is 14°is compared to the stretch fabric in which the included angle betweenthe sinker loop of the hard yarn (nylon) and the knitting direction is7°, the sagging area of the former is small, and the snap backperformance is more excellent.(5) It can be seen from Example 1 and Example 5 that, under the sameconditions, the stretch fabric in which the included angle between thesinker loop of the spandex and the knitting direction is 11° (exceeding10°) is compared to the stretch fabric in which the included anglebetween the sinker loop of the spandex and the knitting direction is 5°,the sagging area of the former is much greater, and the snap backperformance is worse.(6) It can be seen from Example 2 and Example 4 that, under the sameconditions, the stretch fabric in which the included angle between thesinker loop of the nylon yarn and the knitting direction is 4° (lessthan 5°) is compared to the stretch fabric in which the included anglebetween the sinker loop of the nylon yarn and the knitting direction is14°, the sagging area of the former is much greater, and the motionfollowability is worse.(7) It can be seen from Example 3 and Example 1 that, under the sameconditions, the stretch fabric in which the included angle between thesinker loop of the spandex and the knitting direction is 12° (exceeding10°) and the included angle between the sinker loop of the nylon and theknitting direction is 4° (less than 5°) is compared to the stretchfabric in which the included angle between the sinker loop of thespandex and the knitting direction is 9° and the included angle betweenthe sinker loop of the nylon and the knitting direction is 14°, thesagging area of the former is much greater, and the snap backperformance is worse.

1-10. (canceled)
 11. A stretch fabric with excellent snap backperformance, wherein the stretch fabric is a warp knitted fabric formedby hard yarns and elastic yarns, wherein an included angle between asinker loop of the elastic yarn and a knitting direction of a needleloop is 0-10°, and the included angle between the sinker loop of thehard yarn and the knitting direction of the needle loop is 5-85°. 12.The stretch fabric according to claim 11, wherein the elastic yarn is apolyurethane fiber.
 13. The stretch fabric according to claim 12,wherein the polyurethane fiber is obtained after reaction of polyetherdiol having a side chain and a diisocyanate compound with two or morediamine compounds, and a molar ratio of ethylenediamine contained in thediamine compound to a branched aliphatic diamine compound having 3 to 5carbon atoms is 98:2 to 82:18.
 14. The stretch fabric according to claim11, wherein content of the elastic yarns is 50-90% by weight.
 15. Thestretch fabric according to claim 11, wherein a density distributionrange of the elastic yarns is 30-200 w/inch.
 16. The stretch fabricaccording to claim 11, wherein the hard yarn is a chemical fiberfilament with an elongation of 5-50%.
 17. The stretch fabric accordingto claim 16, wherein fineness of the hard yarn is 10 to 100 denier. 18.The stretch fabric according to claim 11, wherein, after the stretchfabric is made into a cylinder having a diameter of 10 cm and a heightof 5 cm, a sagging area formed by depression of a contour portion of thestretch fabric is not greater than 2 cm² under a condition of 50%elongation and 3 times/second speed expansion and contraction.
 19. Thestretch fabric according to claim 11, wherein, when wearing the clothesmade of the stretch fabric, a clothes pressure at the middle of a thighregion in a static state is measured as 1.5-2.0 kPa, and a recoverystress of the stretch fabric at a corresponding portion is 1.5-3.0 N.20. The stretch fabric according to claim 11, wherein a tear strength ofthe stretch fabric is measured as 9.8 N or more under test conditions ofJIS L 1096:2010 D method; and under test conditions of the JIS L1096:2010 A method, a burst strength of the stretch fabric is measuredas greater than 290 kPa.